— Replacing weekly servings of bacon or hot dogs with nuts and legumes linked to reduced dementia risk

PHILADELPHIA – A long-term observational study involving 130,000 healthcare professionals found that eating processed red meat twice a week over several decades was associated with a higher likelihood of developing dementia.

Participants from the Nurses' Health Study and the Health Professionals Follow-Up Study who consumed at least one-quarter of a daily serving of processed red meat — roughly two servings weekly — had a 14% increased risk of dementia, compared to individuals eating less than a tenth of a daily serving, according to Yuhan Li, MHS, from Harvard T.H. Chan School of Public Health. Li presented these findings during the Alzheimer’s Association International Conference.

Each additional daily serving of processed red meat was linked to 1.61 more years of cognitive aging for global cognition, and 1.69 more years for verbal memory. A portion of processed red meat was defined as two slices of bacon, one hot dog, or 2 ounces of sausage, salami, or similar items, Li noted.

Interestingly, when a daily serving of processed red meat was replaced with a serving of nuts or legumes, the risk of dementia dropped by 20%, and global cognitive aging reduced by around 1.37 years, Li reported. Examples of a serving included one tablespoon of peanut butter, one ounce of nuts, or an 8-ounce serving of soy milk.

No significant relationship was found between unprocessed red meat, such as steak or hamburger, and dementia. However, consuming one or more daily servings of unprocessed red meat was associated with a 16% increase in subjective cognitive decline, compared to those who consumed less than half a serving per day.

"There has been some inconsistency on whether there’s a link between meat consumption and cognitive health, so we wanted to take a closer look at the impact of both processed and unprocessed meat on cognitive risks," Li explained.

Li further indicated that processed red meat has also been documented to increase the risk of conditions like cancer, heart disease, and diabetes. The potential negative effect on the brain may be related to its high levels of sodium and nitrites.

Prior research from the Nurses' Health Study and the Health Professionals Follow-Up Study has linked heart-healthy foods like olive oil with reduced dementia-related deaths. Data from the U.K. Biobank also suggested that higher intake of ultra-processed foods was correlated with a greater incidence of dementia, while healthier dietary choices were linked to lower dementia risk.

However, these are all observational studies, meaning they are prone to potential reporting biases and confounding factors. Now, clinical trials are evaluating whether lifestyle adjustments, including diet, can directly influence brain health.

One ongoing trial is the POINTER study, which involves 2,000 older adults. This study is designed to offer "more definitive, data-driven answers about how lifestyle factors, including diet, affect cognitive performance in older individuals," said Heather Snyder, PhD, of the Alzheimer’s Association. The trial is expected to conclude in 2025.

For the current analysis, Li's team examined dietary patterns and dementia onset in 87,424 women from the Nurses' Health Study (1980-2023) and 46,347 men from the Health Professionals Follow-Up Study (1986-2023).

Researchers assessed long-term eating habits through food frequency questionnaires gathered every 2-4 years, with dementia identified by self-reports and dementia-related deaths. Cognitive abilities and memory were evaluated using tools like the Telephone Interview for Cognitive Status (TICS) among 17,458 women. Cognitive decline was tracked via questionnaires filled out by 33,908 women and 10,058 men.

A major limitation of the study is its focus on specific diet components, with unknown adjustments for other factors. Additionally, its observational design prevents the establishment of causation between processed red meat consumption and dementia.

Disclosures

This research was supported by the NIH.

Neither Li nor Snyder reported any disclosures.

Primary Source

Alzheimer's Association International Conference

Source Reference: Li Y, et al. "A prospective study of long-term red meat intake, risk of dementia, and cognitive function in U.S. adults" AAIC 2024.